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take_while.ts
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take_while.ts
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// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
// This module is browser compatible.
/**
* Returns all elements in the given collection until the first element that
* does not match the given predicate.
*
* @example
* ```ts
* import { takeWhile } from "https://deno.land/std@$STD_VERSION/collections/take_while.ts";
* import { assertEquals } from "https://deno.land/std@$STD_VERSION/assert/assert_equals.ts";
*
* const arr = [1, 2, 3, 4, 5, 6];
*
* assertEquals(
* takeWhile(arr, (i) => i !== 4),
* [1, 2, 3],
* );
* ```
*/
export function takeWhile<T>(
array: readonly T[],
predicate: (el: T) => boolean,
): T[] {
let offset = 0;
const length = array.length;
while (length > offset && predicate(array[offset])) {
offset++;
}
return array.slice(0, offset);
}